Technical Field
The present disclosure relates to a method for manufacturing a catalyst layer. More particularly, the present disclosure relates to a method for manufacturing a catalyst layer by using a sol-gel method accompanied with a polymerization-induced phase separation, a catalyst layer, a membrane electrode assembly and a manufacturing method thereof, and a fuel cell using the same.
Description of Related Art
Energy is the source of all economic activity and highly correlates to the development of social economy. To date, most of the energy sources in the world are produced from fossil fuel (such as petrol or gas), hydropower, geothermal energy, nuclear energy and solar energy. The highest ratio is from fossil energy, but burning fossil fuel will produce CO2, SOx and NOx pollution. In the past, the abovementioned types of energy were applied broadly for enhancing the economic growth. However, it resulted in terrible air pollution and global warming. Therefore, scientists are eager to look for the solution for reducing the use of the traditional energy. Fuel cells will be one of the most important, potential and practical choices.
The fuel cell is a galvanic cell which converts fuel and gas oxidizing agent to electrical power and produces some products. In other words, the fuel cell converts chemical energy to electrical power directly. Further, the produced waste gas is water vapor, which will not pollute the environment, and it may not need thermal energy to complete the conversion. For this reason, it is one of the clean and high efficiency green energies. Please refer to FIG. 1, which shows a structural schematic diagram of a conventional proton exchange membrane fuel cell unit 100. A proton exchange membrane fuel cell (not shown) includes at least one proton exchange membrane fuel cell unit 100. The proton exchange membrane fuel cell unit 100 includes an anodic bipolar plate 102a, a cathodic bipolar plate 102b, an anodic gas diffusion layer 104a, a cathodic gas diffusion layer 104b, an anodic catalyst layer 106a, a cathodic catalyst layer 106b, a proton exchange membrane 108 and related attachments, such as a blower (now shown), valves (not shown), channels (not shown in the figure) and so on.
Accordingly, the anodic gas diffusion layer 104a, the cathodic gas diffusion layer 104b, the anodic catalyst layer 106a, the cathodic catalyst layer 106b, the proton exchange membrane 108 are the core of the proton exchange membrane fuel cell unit 100 and they are usually combined to form a membrane electrode assembly. The anodic catalyst layer 106a includes an anodic catalyst support 106aa and anodic catalyst 106ab deposited thereon. The cathodic catalyst layer 106b includes a cathodic catalyst support 106ba and cathodic catalyst 106bb deposited thereon. Usually, precious metal particles exhibiting catalyst activity, such as platinum particles, are used as the abovementioned catalysts (106ab and 106bb), and carbon particles are used as the catalyst supports (106aa and 106ba). The platinum particles and the carbon particles are coated, respectively, onto the surface of the anodic gas diffusion layer 104a and the cathodic gas diffusion layer 104b. 
However, the usage of the carbon particles as the catalyst supports in the proton exchange membrane fuel cell may produce CO intermediate during the oxidization so as to reduce the efficiency. Even a trace of CO will easily attach on the surface of the platinum particles and reduce the active surface site of the catalyst since CO has a better bonding ability with the platinum particles than hydrogen gas. That is, it is a CO poisoning effect of the catalyst layer in the proton exchange membrane fuel cell. Furthermore, the manufacturing process of using the carbon particles as the catalyst support requires a high thermal energy, which is higher than 1000° C., and the precious metal particles are expensive. All these issues make the proton exchange membrane fuel cell can hardly cost down and are also against the mass production.